CacheStorage: Fix tracing id bit mask.

Bug: 927538
Change-Id: I166ccaa795736e96127aa2dc0526b2650cfeb0ba
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1526464
Commit-Queue: Daniel Murphy <dmurph@chromium.org>
Reviewed-by: Daniel Murphy <dmurph@chromium.org>
Cr-Commit-Position: refs/heads/master@{#642140}
1 file changed